[PATCH] Reproducible oops in 2.4.10, khttpd crashing when apache is not running ; corresponding HTTP error message

[PATCH] Reproducible oops in 2.4.10, khttpd crashing when apache is not running ; corresponding HTTP error message

[Rui Ribeiro]

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Howdy,

First I would like to say hello to everyone in this list.

I'm running kernel 2.4.10 (Intel), and performing experiments with the 
khttpd server compiled as a module. I am writing to this list concerning a 
couple of things I noticed in khttpd, and offering a fix. I already sent this e-mail 
to the list, but not with a standard subject.
 
Problem description:
-----------------------------

I began noticing that it crashed with a  oops  or hanging the 
machine when apache was not running. When the machine survived, it also 
returned a 403 error,  with a "Permission denied" message.


The hack:
------------------

Upon source investigation, I noticed that at 
/usr/src/linux/net/khttpd/userspace.c, at the function Userspace, in the 
place where's the user-daemon no present case is coded, a structure element 
is not released.

After correction, I have also changed the 403 error (permission denied), to 
a 503 Service Unavailable, as I believe it's more correct. If the khttpd 
daemon can't call Apache (or other userspace daemon) when it's not capable 
of processing the request, it's better to give a 503 message than a 403, 
for  my and the users'  sanity sake.

So, in the  2.4.10 kernel source tree, in the already mentioned 
/usr/src/linux/net/khttpd/userspace.c, at line 114, you can make the 
following changes:

Send403(CurrentRequest->sock); to Send50x(CurrentRequest-sock);

Append the following lines after the Send50x:
sock_release(CurrentRequest->sock);
CurrentRequest->sock=NULL;


This patch has already been tested by another two persorns.

A diff file is included as an attachment.


Regards,
--
Rui Ribeiro
Network and Security consultant
http://www.case.pt


P.S. A copy of this message has already been sent to khttpd users list.

 

[-- Attachment #2: userspace.diff --]
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101d100
< 
102a102
> 			
113,119c113,115
< 	
< /* Rui */
< 			Send50x(CurrentRequest->sock); /* Sorry, no go... */
< 			sock_release(CurrentRequest->sock);
< 			CurrentRequest->sock = NULL;	 /* We no longer own it */
< /* End Rui */
< 
---
> 			
> 			Send403(CurrentRequest->sock); /* Sorry, no go... */
>